• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.529-535
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• 2000

In this paper, a current control system of a single phase PWM AC/DC converter using a reduced-order Luenberger observer without source voltage sensors is proposed. The sinusoidal input current and unity input power factor are realised based on the estimated source voltage performed by the reduced-order Luenberger observer using actual currents and DC link voltage. The poles of the reduced-order Luenberger observer are placed in the left half plane of s-plane by the pole-placement method in order to acquire the stability of the observer. The magnitude and the phase of the estimated source voltage are used to accomplish the unity power factor. The proposed method is implemented by DSP(Digital Signal Processor). Experimental Results verify that the reduced-order observer estimates the source voltage without the estimation error and the control system accomplishes the unity power factor, and constant DC link voltage.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.123-126
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• 2000

When LC filter is connected parallel to the Active Power Filter a problem of the resonance between the Active Power Filter(AF) and LC filte often arises. in this paper Deadbeat control of Hybrid Active Power Filter using Disturbance-observer is introduced to solve this problem. By the estimation of the harmonics disturbance using proposed disturbance observer the compensation characteristics of the AF is improved and the resonant current is suppressed. The validity of proposed disturbance observer is verified from simulation results using PSIM

• Journal of Power Electronics
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• v.11 no.3
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• pp.304-310
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• 2011

The power series approximation method is proposed for real time implementations of a discrete flux observer. The proposed method improves the performance of the discrete flux observer in the case of a low sampling rate and high speed range, where the simple discrete flux observer converted by the Euler method cannot estimate the actual flux precisely. The performance of discrete flux observers with different orders of approximation is compared to find out the proper order of approximation. The validity of the proposed method is verified through simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.6
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• pp.565-572
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• 2013

The sensorless speed control using the improved full-order flux observer for PMSM is proposed in this paper. A conventional full-order flux observer has a drawback that the estimated flux of this observer contains the ripple component at the low speed range due to the increased gains of the convectional full-order flux observer. The improved full-order flux observer with the modified gains guarantee the improved estimation performance without ripple component at the from zero to high speed range. To identify the performance of proposed observer, the simulation and experiment are conducted and this performance is compared with the conventional full-order observer.

• Journal of Power Electronics
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• v.14 no.1
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• pp.125-134
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• 2014

This paper presents a robust and speed-sensorless stator flux estimation for induction motor direct torque control. The proposed observer is based on sliding mode approach. Stator electrical equations are used in the rotor orientation reference frame to eliminate the observer dependence on rotor speed. Lyapunov's concept for systems stability is adopted to confine the observer gain. Furthermore, the sensitivity of the observer to parameter mismatch is recovered with an adaptation technique. The nonlinearities of the pulse width modulation voltage source inverter are estimated and compensated to enhance stability at low speeds. Therefore, a new method based on the model reference adaptive system is proposed. Simulation and experimental results are shown to verify the feasibility and effectiveness of the proposed algorithms.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1346-1354
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• 2016

This paper proposes a design guideline for the feedback gain of the adaptive full-order observer in the speed sensorless control of induction machines. The performance of the adaptive full-order observer is dependent on its feedback gain. This paper presents a pole placement method for the observer feedback gain design to improve the estimation performance of the speed adaptive observer. In the proposed method, the observer poles can be chosen independently of the induction motor poles. Instead, they can be positioned according to the operating speed. An analysis and experimental results obtained with the proposed method reveals better performances under general operating conditions.

• Journal of Power Electronics
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• v.9 no.1
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• pp.117-123
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• 2009

This paper presents a sliding mode observer for the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives. The sliding mode observer has been presented as a robust estimation method. Most of these previous works, however, were not for an interior PMSM (IPMSM), but for a non-salient pole PMSM and its observer design is conducted in the stationary reference frame. Thus, in this paper, we investigate the design of a sliding mode observer and its driving characteristics for an IPMSM. The proposed sliding mode observer is designed in the rotating reference frame, and good drive performance is achieved even when the observer parameters are mismatched with those of an actual motor. The proposed method is applied to a 600W IPMSM, and, then, the measurement results are presented.

• Journal of Power Electronics
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• v.10 no.5
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• pp.498-504
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• 2010

The output power fluctuations of renewable energy power plants such as wind turbine generators and photovoltaic systems result in frequency deviations and terminal voltage fluctuations. Furthermore, these power fluctuations also affect the turbine shaftings of diesel generators and gas-turbine generators which are the main power generation systems on isolated islands. Therefore, it is important to achieve torsional torque suppression. Since the measurement of torsional torque is technically difficult, and there is an uncertainty in the mechanical constants of the shaft torsional system. This paper presents an estimation system that estimates torsional torque by using a developed $H_{\infty}$ observer. In addition to the above functions, the proposed shaft torque observer incorporates a parameter identification system that aims to improve the estimation accuracy. The simulation results validate the effectiveness of the proposed $H_{\infty}$ observer and the parameter identification.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1442-1447
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• 2012

In this paper, direct power control system for three-phase PWM AC/DC converter without the source voltage sensors is proposed. The sinusoidal input current and unity effective power factor are realised based on the estimated flux in the observer. Both active and reactive power calculated using estimated flux. The estimation of flux is performed based on the Reduced-order flux observer using the actual currents and the command control voltage. The source voltage sensors are replaced by a flux estimator. The active and reactive powers estimation are performed based on the estimated flux and Phase anble. The proposed algorithm is verified through simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.411-419
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• 2005

In this paper, a sliding mode observer for solar array current estimation in the photovoltaic power generation system is presented. The solar array current estimation Information is obtained from the sliding mode observer and fed into the maximum power point tracker to update the reference voltage. The parameter values such as inverter dc link capacitances cm be changed up to 50$\%$ from their nominal values and the linear observer can't estimate the correct state values under the parameter variations and noisy environments. The configuration of sliding mode observer is simple, but it shows the robust tracking performance against parameter variations and modeling uncertainties. In this paper, the method for constructing the sliding mode observer using equivalent control input is presented and the convergence of the proposed observer is verified by the Lyapunov method. The mathematical modeling and the experimental results verify the validity of the proposed method.